Installation guide

Create a RAID device
Create a multipath device
22.3.1. Creat ing a RAID Device Wit h mdadm
To create a RAID device, edit the /etc/mdadm.conf file to define appropriate DEVICE and ARRAY
values:
DEVICE /dev/sd[abcd]1
ARRAY /dev/md0 devices=/dev/sda1,/dev/sdb1,/dev/sdc1,/dev/sdd1
In this example, the DEVICE line is using traditional file name globbing (refer to the glob(7) man
page for more information) to define the following SCSI devices:
/dev/sda1
/dev/sdb1
/dev/sdc1
/dev/sdd1
The ARRAY line defines a RAID device (/dev/md0) that is comprised of the SCSI devices defined by
the DEVICE line.
Prior to the creation or usage of any RAID devices, the /proc/mdstat file shows no active RAID
devices:
Personalities :
read_ahead not set
Event: 0
unused devices: none
Next, use the above configuration and the mdadm command to create a RAID 0 array:
mdadm -C /dev/md0 --level=raid0 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 \
/dev/sdd1
Continue creating array? yes
mdadm: array /dev/md0 started.
Once created, the RAID device can be queried at any time to provide status information. The
following example shows the output from the command mdadm --detail /dev/md0:
/dev/md0:
Version : 00.90.00
Creation Time : Mon Mar 1 13:49:10 2004
Raid Level : raid0
Array Size : 15621632 (14.90 GiB 15.100 GB)
Raid Devices : 4
Total Devices : 4
Preferred Minor : 0
Persistence : Superblock is persistent
Update Time : Mon Mar 1 13:49:10 2004
State : dirty, no-errors
Active Devices : 4
Working Devices : 4
Failed Devices : 0
⁠Chapt er 2 2 . Addit ional Informat ion for IBM Syst em z Users
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